Caking bomb assembly



M. D. BARNQES ETAL 7,946

CAKING BOMB ASSEMBLY Original Filed Aug. 8, 1951 May 26, 1959 FIG. I & 2 q, s e 9 a 2 W: 71 o 0 l Marlon D. Barnes James P. Leo

INVENTOR.

ATTORNEY "2,887 945. :Patented May 26, .1959

887 CAKING BOlVIB ASSEMBLY Marion 1). Barnes and James P. Lea, El Dorado, Ark.,

assignors, by mesne assignments, to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware Original application August 8, 1951, Serial No. 240,942, now Patent No. 2,762,294, dated September 11, 1956. Divided and this application November 14, 1955, Serial No. 547,254

1 Claim. (Cl. 100-99) This invention relates to a caking bomb assembly, and more particularly to an apparatus for simultaneously preparing a plurality of specimens in the form of compressed cakes.

Considerable efl'ort has been made in the fertilizer industry to minimize the tendency of fertilizers to cake. while much progress has been made along this line, the caking problem still exists. For instance, ammonium nitrate is manufactured in the form of pellets and the pellets coated in order to reduce caking. In view of the foregoing, as a control measure, it is necessary to provide means for preparing a large number of specimens for making caking tests. Accordingly, the present invention relates to an apparatus for preparing such specimens.

Although not limited to such application, the invention will be described with reference to apparatus particularly adapted for simulating the conditions to which bagged fertilizer is subjected during storage in order to determine the caking properties thereof. For this purpose, fertilizer is pressed into cakes under controlled conditions as to pressure, temperature, and humidity during a period of about one week. Tendency to cake then is measured as the pressure required to crush the cakes, as in a Carver laboratory press.

This invention will be understood more readily from the following description of apparatus forming various embodiments thereof.

Referring to the drawings generally:

' Figure 1 is a side elevation, partly in section, of a caking bomb and assembly rack of this invention.

Figure 2 is a plan view on line 2-2 of Figure 1.

Figure 3 is a section view on line 33 of Figure 1 showing details of the cup in which the cakes are formed.

Figure 4 shows the use of a spring in the apparatus of Figure 1 for maintaining the pressure constant.

Referring to the drawings in greater detail:

Numeral 1 represents a rack or frame adapted to accommodate any desired number of bombs 2. Each bomb unit comprises metallic double wall bellows 3 to which is securely attached a head 4 held in the opening 5 of the rack with cotter pins 6 and communicating with the bellows through a tapped opening 7 into which a pressure gauge 8 is threaded. 'Ihe bellows is filled with a fluid such as an organic fluid (e.g. mineral oil, dibutyl phthalate), water, or air in order to transmit the pressure to the gauge which is applied to the cake 9 by tightening the jack screw 10 threaded into the base plate 11 of the rack.

The cake-fomiing cup 12 of the bomb comprises an outer pipe 13 into the bottom of which is threaded an ordinary barrel bung 14 having a rod 15 attached in the well thereof more or less as a filler. Resting unattached on .top of the ,bunglis a metal plate 16 ofsubstantially the same diameter as-theinside diameter of the outer pipe 13. A pipe 17 split in half longitudinally fits inside the outer pipe 13 and rests on the plate 16. The material, e.g. ammonium nitrate pellets 18, to be pressed is placed in the cup 12 thus formed and a metal plate 19 is laid on top of the material. As indicated above, the desired pressure is applied to the ammonium nitrate by tightening the jack screws 10.

The entire assembly of bombs and the rack are placed in a cabinet (not shown) and the ammonium nitrate is subjected to controlled conditions as to pressure, temperature and humidity for about one week. Then the ammonium nitrate cakes formed are removed from the bomb by loosening the jack screw 10, removing the cakeforming cup 12 from between the jack screw and bellows, and removing each half of the split pipe 17. Tendency of the ammonium nitrate to cake is then determined by measuring the pressure required to crush the cakes, e.g. in a Carver laboratory press.

In connection with the above described apparatus, it was found in most cases that during about the first day of the cake-forming operation the ammonium nitrate would settle, thereby causing a decrease in volume and a corresponding drop in pressure. In order to maintain a reasonably constant pressure, this made it necessary for the operator to check the bombs periodically and compensate for the pressure drop by tightening the jack screws 10.

In order to enable the application of a more nearly uniform pressure automatically, a resilient material, such as a spring 34 as shown in Figure 4, is attached to the bellows. The spring is under compression at the start of the cake-forming operation and compensates for any decrease in volume caused by settling of the ammonium nitrate and thereby maintains the pressure substantially constant. Although a spring is preferred, other resilient materials such as rubber can be used.

Although less desired, alternatively the resilient material can simultaneously serve the dual function of applying the pressure and stabilizing it. Thus as a means of applying pressure, it can be used instead of the jack screw and other means of applying pressure, or it can be used in conjunction therewith.

This application is a division of application Serial No. 240,942, filed August 8, 1951, now US. Patent 2,762,294.

What is claimed is:

Apparatus for preparing a plurality of test samples of granular material simultaneously under simulated storage conditions which tend to cause said granulator material to coalesce comprising a frame, said frame having flat top and bottom members supported by connecting side members, a series of fluid filled pressure responsive metallic bellows depending from said top member, a series of compression springs secured to the free ends of said bellows, pressure indicating means communicating with said bellows, a series of cylinder assemblies supported by said bottom member in alignment each with one of said depending bellows and the springs mounted thereon, said cylinder assemblies each being comprised of an upstanding outer cylinder, a bottom closure detachably secured in the lower end of said outer cylinder, an unattached bottom disk of less diameter than said outer cylinder resting upon said bottom closure, a divided cylindrical insert resting upon said bottom disk and protruding above the free end of said cylinder, and a top pressure disk of less diameter than said insert having sliding contact with the inner walls thereof, means for ap plying pressure to the samples of granular material disposed between said top pressure disk and said bottom disk of said cylinder assemblies, said top disk having contact with the free ends of said springs mounted on said depending bellows upon the application of pressure to said samples whereby the pressure exerted on the samples of material disposed in said cylinder assemblies is maintained constant during the gradual coalescence'of said granular material during prolonged exposure there- 10 2,642,797

. r w s of to other simulated conditions such as temperature and humidity likely to be encountered-inthe storage thereof.

References Cited in the file of this patent UNITED STATES PATENTS 877,139 Tatarinofl Jan. 21, 1906 2,245,080 Pendleton June 10, 1941 2,325,027 Anway July 27, 1943 "2,471,227 Marshall May 24, 1949 Peters June 23, 1953 

